By sion932 
GB/T 22716-2008 is a national recommended standard in the People’s Republic of China, specifically formulated to regulate the test methods and limit values for the interturn insulation of armature windings in DC electrical machines. Issued on December 30, 2008, and officially implemented on October 1, 2009, this standard plays a crucial role in ensuring the reliability and safety of DC motor operations by establishing rigorous technical criteria for interturn insulation testing. This article provides a comprehensive overview of the core content, application scope, and key technical requirements of GB/T 22716-2008.
1. Basic Information of the Standard
The standard is classified under the Chinese Standard Classification (CCS) number K23 (DC Motors) and the International Standard Classification (ICS) number 29.160.30 (Electric Motors). It is proposed by the China Electrical Equipment Industrial Association and supervised by the National Technical Committee for Rotating Electrical Machines (SAC/TC 26). The main drafting units include Shanghai Electrical Apparatus Research Institute (Group) Co., Ltd., Shanghai Electric Motor Technology Co., Ltd., Jiangmen Jiangzhan Electric Motor Factory Co., Ltd., and other well-known enterprises and research institutions in the electrical machinery industry, ensuring the standard’s authority and practical applicability.
2. Scope of Application
GB/T 22716-2008 applies to the interturn insulation withstand voltage tests of armature windings for DC electrical machines with a rated voltage of 110V and above. For other types of DC electrical machines, unless there are special requirements, they should also be tested in accordance with the provisions of this standard. It should be noted that this standard does not apply to micro-motors. The clear definition of the application scope helps to avoid ambiguity in practical application and ensures that the test work is carried out in a targeted manner.
3. Key Terms and Definitions
To ensure the consistency of understanding and implementation of the standard, GB/T 22716-2008 defines two core test methods related to interturn insulation testing:
- Setover Method: A test method for the interturn insulation of DC motor armature windings using impulse voltage. During the test, a span is selected on the armature commutator, and impulse voltage is applied between the commutator segments at both ends of the span.
- Segment Method: Another impulse voltage-based test method for interturn insulation. Unlike the setover method, this method applies impulse voltage between two adjacent commutator segments on the armature commutator.
4. Core Test Requirements
The standard divides the interturn insulation tests of armature windings into three main stages: pre-installation inspection test of coils, post-installation inspection test of coils, and interturn impulse withstand voltage test of DC motors (armature windings). Each stage has clear test purposes, requirements, methods, and limit values.
4.1 Pre-installation Inspection Test of Coils
The purpose of this test is to control the quality of the interturn insulation of individual coils before they are installed into the stator core. Key requirements and specifications are as follows:
- Test Conditions: The test should simulate the actual state of the coil in the stator core slot. The turns of the test coil should be fixed, and the coil should be placed on a rack with good insulation to the ground.
- Test Exemption Criteria: For general-purpose motors with a rated voltage of 660V and below, if the quality of the interturn insulation is stable and mass production has been achieved, individual coils and equalizer wires generally do not need to undergo pre-installation interturn withstand voltage tests. However, for large motors (with an armature outer diameter of 990mm and above), special-purpose motors such as hoisting and metallurgical motors, and motors with a rated voltage above 660V, pre-installation interturn withstand voltage tests for individual coils and equalizer wires are mandatory.
- Test Methods and Limits:
- For interturn withstand voltage tests between different coil units: Power frequency voltage or DC voltage is preferred. The test voltage is applied between two adjacent turns. For general-purpose motors with a rated voltage of 660V and below, the effective value of the power frequency test voltage should not be less than 220V, and the DC test voltage should not be less than 400V. For special-purpose motors such as hoisting and metallurgical motors and motors with a rated voltage above 660V, the effective value of the power frequency test voltage should not be less than 530V, and the DC test voltage should not be less than 960V. The test duration for both power frequency and DC voltage is 1 to 3 seconds.
- For interturn withstand voltage tests of the same coil unit: Impulse voltage generated by capacitor discharge is directly applied between the leads of the test coil. The peak value of the impulse voltage for each coil unit should not be less than 700V, and the number of impulses should not be less than 5 times.
4.2 Post-installation Inspection Test of Coils
This test is conducted to assess the quality of the interturn insulation of the armature winding after the coils are installed and banded, but before impregnation. It can also be performed at other stages of armature winding manufacturing as needed.
Test Methods: Impulse voltage generated by capacitor discharge is directly applied between the commutator segments, and the armature shaft must be grounded during the test. The judgment of interturn short circuits can adopt the waveform comparison method, where the waveform of the test winding is compared with the normal waveform; consistency indicates qualification. Other effective judgment methods are also acceptable. The specific test method should be selected according to the type of winding:
- Setover Method: The number of commutator segments within the selected span should be determined based on the winding type and test equipment to ensure that the peak value of the impulse voltage between segments meets the requirements. Generally, 5 to 7 segments are recommended. The test voltage applied to the sample should be less than 1.8 times the effective value of the factory power frequency test voltage for ground insulation. To ensure that each segment undergoes the same voltage test conditions, it is recommended to test each segment one by one (the number of tests can be reduced according to the connection method of the equalizer wires).
- Segment Method: Tests are conducted sequentially on each pair of adjacent commutator segments. If high induced voltage is generated in the untested coils during the test, grounding devices should be installed on the commutator segments on both sides of the test segments and properly grounded.
Test Limits: For general-purpose motors with a rated voltage of 660V and below, the peak value of the interturn impulse voltage between segments should not be less than 350V. For special-purpose motors such as hoisting and metallurgical motors and motors with a rated voltage above 660V, the peak value should not be less than 500V. In both cases, the number of impulses should not be less than 5 times.
4.3 Interturn Impulse Withstand Voltage Test of DC Motors (Armature Windings)
DC motors (armature windings) must undergo the interturn impulse withstand voltage test in accordance with the provisions of 5.3 and 5.4 of the standard before final assembly. This test is generally performed after the armature windings are installed and banded but before impregnation, ensuring that the interturn insulation performance of the armature windings meets the requirements before the motor is fully assembled.
5. Significance and Application Value
The interturn insulation of the armature winding is a critical component affecting the service life and operational safety of DC motors. Defects in interturn insulation can lead to interturn short circuits, which may cause motor damage or even serious safety accidents. GB/T 22716-2008 provides a unified and standardized testing framework for manufacturers and testing institutions in the electrical machinery industry. By strictly implementing this standard, enterprises can effectively identify potential defects in the interturn insulation of armature windings during the production process, improve product quality, and reduce the risk of failures during motor operation. Meanwhile, the standard also provides a reliable technical basis for the supervision and inspection of DC motor products, promoting the healthy and orderly development of the electrical machinery industry.
GB/T 22716-2008 is an important technical standard in the field of DC electrical machines, focusing on the interturn insulation testing of armature windings. With its clear application scope, rigorous test methods, and specific limit values, the standard effectively guarantees the reliability and safety of DC motors. For relevant enterprises and technical personnel in the electrical machinery industry, a thorough understanding and strict implementation of GB/T 22716-2008 are essential for improving product quality and maintaining the stable operation of equipment. As the electrical machinery industry continues to develop, this standard will remain an important basis for regulating interturn insulation testing and promoting technological progress in the industry.
References
[1] GB/T 22716-2008, Test Specifications of Interturn Insulation of Armature Winding for DC Electrical Machines[S]. Beijing: China Standards Press, 2009.